The EPA has denied a request made by NRDC to ban 2,4-D, one of the top-selling and most widely-used herbicides in the country that was also a key ingredient in Agent Orange.

NRDC had petitioned the agency in 2008 to revoke all 85 of the 2,4-D tolerances (meaning legal residue limits in food) and product registrations, citing studies pointing to links between 2,4-D and cancer, hormone disruption, genetic mutations and neurotoxicity.

The EPA said in its decision that it "evaluated all the data cited by NRDC and new studies submitted to EPA in response to the reregistration decision," and that "EPA’s comprehensive review confirmed EPA’s previous finding that the 2,4-D tolerances are safe."

The safety standard, however, may not be the strictest. And the agency's proof of safety is not the most reliable. More from The New York Times:

In its ruling, the E.P.A. said that while some studies cited suggested that high doses of the chemical could be harmful, they did not establish lack of safety, and in some cases they were contradicted by other studies.

The agency in particular cited a study, financed by the 2,4-D manufacturers and conducted by Dow, in which the chemical was put into the feed of rats. The study did not show reproductive problems in the rats or problems in their offspring that might be expected if 2,4-D were disrupting hormone activity, the E.P.A. said.

Research by the EPA found that babies born in counties with high rates of 2,4-D application to farm fields were significantly more likely to be born with birth defects of the respiratory and circulatory systems, as well as defects of the musculoskeletal system like clubfoot, fused digits and extra digits. These birth defects were 60% to 90% more likely in counties with higher 2,4-D application rates.

The results also showed a higher likelihood of birth defects in babies conceived in the spring, when herbicide application rates peak.

NRDC had petitioned the agency in 2008 to revoke all 2,4-D tolerances and product registrations, citing studies pointing to links between 2,4-D and cancer, hormone disruption, genetic mutations and neurotoxicity.